The present invention relates to semiconductor devices and semiconductor device manufacturing methods.
In order to improve the characteristics of semiconductor devices, various technologies relating to the laminated structures of gate insulating films and semiconductor layers have been disclosed.
The patent literature 1 (Japanese Unexamined Patent Application Publication No. 2006-269641) discloses the following semiconductor device. The semiconductor device includes a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) in which SiC is used. The P-channel MOSFET has a gate oxide film made of SiO2, and the gate oxide film includes hydrogen atoms or hydroxyl groups with their concentrations in a range of 1×1019 cm−3 to 1×1022 cm−3. In addition, the patent literature 1 discloses that, after an oxide film is formed, the gate oxide film is formed by thermally oxidizing the oxide film in an atmosphere including H2O.
The patent literature 2 (Japanese Unexamined Patent Application Publication No. 2008-244456) discloses the following semiconductor device including SiC. A hydrogen concentration at an interface region between a channel region and a gate insulating film of the semiconductor device is 4.7×1020 cm−3 or larger. In addition, in the patent literature 2, dangling bonds at the interface region are assumed to be hydrogen-terminated or hydroxyl-terminated.
The patent literature 3 (Japanese Unexamined Patent Application Publication No. 2005-72490) discloses a forming method of a dielectric film. In the paragraph 0007 of the patent literature 3, it is described that, if an aluminum oxide film is formed by means of an atomic layer CVD method (referred to as an ALD method hereinafter) with the use of trimethyl aluminum (TMA) and water as materials, hydrogen atoms are included in the aluminum oxide film with their concentration in a range of 1×1020 cm−3 to 1×1021 cm−3 as component elements of hydroxyl groups. In addition, this patent literature states that the above description relates to a gate insulating film of a silicon transistor. It is alleged that the above described hydroxyl groups in a silicon transistor are apt to be desorbed in the following post-process, and that the characteristics of the semiconductor are adversely affected.
The patent literature 4 (Japanese Unexamined Patent Application Publication No. 2010-98141) discloses that a gate insulating film made of aluminum oxide is formed by means of the ALD (Atomic Layer Deposition) method with the use of TMA, and O2 or O3 over a GaN semiconductor layer.
The patent literature 5 (Japanese Unexamined Patent Application Publication No. 2006-253224) discloses that, in a nitride semiconductor device, hydrogen atoms are segregated not in a gate insulating film, but in a channel region of a group III nitride semiconductor layer which is doped with Mg.